Floating tool holder



March 11,195s H. Q. MUNN 2,826,053

FLOATING TOOL HOLDER 2 Sheets-Sheet. 2

Filed July 11, 1955 INVENTOR. ,V4/wey Q. Mww/ BY Ma/QM@ Tranen/EY UnitedStates Patent() FLOATING TOOLr HQLDER` Harry Q. Munn, Birmingham,Mich.Application VJuly 11, 1955', Serial No.f52'1,303 3,'Cllims.` t (Cl..G4-3,1)

T'Ihis invention relates to an improved floating vtool holder orcouplingand more particularly to a novel yform lof liio'ating tool- -holderconstructionwherein the axis of fthedrivingmember and the axis of thedriven member sare maintained `parallelto one'anothe'rfat all timeswhile these members are free to moverelatively to one` an-'armachineandf the driven member topmean the member ladapted to thetool.

In prior attempts to achieve these-characteristicsvball thrusta racesconsisting; of-at racesv separatedbyfballshave 'Sheen usedaforfapplyingfaxial pressure tothe 'moving parts and maintaining parallelism; and pinssupporting; rollers engaging .slots have been usedstoV transmit thetorque required` in operation.

In the case of flat races the surfaces become `'slightly .indentedfby'they balls duetheir points off Contact causing uwear. andfimpairing;theirl functioning; whilel in 4thescas'e `.ofzfdItis/.ingvpins.with:rollersrlthere is considerable friction Ibetween'theA rollerand its supporting pin asi-wellrfassbe- Ytween the Vroller and its:mating slot.

-In', the present invention Ait is` the primary object to overcome;these.i diiculties Vbyuemploying a. novel structureywherein.afseriesofballsor rollersl or balls. and rollers.Qmbijlgledmaybe employed foractuallyspacing apart the'.essential.yelements:v of the; tooltholder `so that there vis nog friction-producingcontact therebetween.

lt;` is; the A"further object ofthe present inventions to pro videelongated, grooves in opposed p parts fofrtheoating toolfholder `with aseries of; balls orrollers-movably mounted; inL said grooves in: suchamanner thatxthereis pnovidedt :multiple lines of contact, between the..`halls. lor rollers and their corresponding grooves.

It ist*A the .further object of the ;presen t; invention:.toJincorporate in@z the floating tool-l holderl construction-a housingretainer, f together with suitable e bearing', .means :betweentheret-,ainer and .the Y driven member, toy therebyaimpart an initial'axial preload*v to,y allmoving parts` to thereby assurethatthrOnghOut theA life of the3tool holderthe `1re- -speetive axes; ofthe; drivingmember andV the'y driven mem.- ber will be in parallelism atallf times.

Sincethe balls or rollers in either -case `engage grooves iu theopposedfessential parts, they/not.onlyresist any fereeftending todeflect thev` axes. of thedrivingandt'driven members? in'relation tovone another, but; theyy resist torsionalflpadi-hetween driving; anddrivenmembers,y thus eliminatingthe vuse of drivingpins. Theseconditions constitute further objects of the present invention. f Ms,therefore,` the further object ofl the-presentinvention `to provide avoatrilrigA toolA holder wherein the; axis of; the drivingV memberf and?thef axis of the: driven member; if misaligned with .respect tooneffanother, willnbe .rev tained at all; rvtirnes in parallelilVrelationto one lanother vtyhilel rotating with respect to `a`workpiece.

It sthezfurther object of the;presentfinventon'to providea,nove1;consu-,union :wherein the-:driven-:memberr2,826,053 Patented Mar. 11,1958 jpended drawings in which:

Fig. 1 is a longitudinal section, of the present, floating tool holder,with a;porti0n of atool fragmentarily shown.

'Figi 2 lis aright endelevational view thereof.

Pig. -3 isa-section, taken on line Seli of Fig. 1.

Fig'. 4 is a seetiontaken online 4-4 of Fig. l.

Fig. 5 is a side elevational view of the iloat or intermediate drivingrace.

`Figw' Yis asection taken on line 6-6Vof Fig, 1,.

Fig.4 7J isa fragmentary and partially diagrammatic View 'illustratingthe use of roller `bearings between the respective parts.

:1"ig."8` `is asimilar-view illustrating the combination of rollerbearings and ball bearings between respectivey parts;

and

Fig. 9 is asimilar viewillustrating a special form of roller bearingsbetween respective parts.

It will beunderstood `that the Aabove drawings illus- `trate-merelythepreferred embodiment of the invention and thatother embodiments arecontemplated withinthe scopeof theclairns`V hereafter setforth.

Referring to-Fig; `l,l therey is provided an elongated` driv--ing-shankfll whichl may be of any desired form suitable foradapting #toa machinewhich Awill apply avptor'que Athereto; and whichisrotatable-'upon itsplongitudnal axis.

`Said shankfhas-at one end an enlarged circular shoulder `112 lwhichterminates in the threaded'end portion 13"and which has' formed thereonthe right angularly vrelated endface 14.

Thekeyway or-slot ISI is arranged centrally within end face '14 andaxially of said keyway there is provided-a threaded bore-16. The discshaped driving race 1*8,l of less -diameter` thant-hread'ed `element 13,is positioned against /end face 14, and has an elongated key-17'ofrectangular cross-section which is nested within keyway -15' andissecured'vthereinby thel screw 20. The drivingA race at, its center has atapered wall portion 19 which cooperatively receives thetaperedundersurface of Vscrew` 20v whereby `the driving race-128`is effectivelycentered and immovably secured-with respecttothethreaded' head 1-3- andend bearings 2'7 in` the manner hereafter described; lThe elongated:retainerfhousingy 21 at;` its open end-isthrea-ded overtthe .threadedend 13.011 shank 1-1 and provides an enclosingrtretainer/for the otherpartsof the oating tool holder hereafter described, and falso. 4keepsdirt-#from :enteringnthe mechanism. The opposit'eend (5f-theretainer`housing includes `a centrally apertured annular 'angez 242. whichthrough certainfbearing elements-where lafter described', `retainingly.engages the.. driven` member forming-a part offthe coupling. y

Pin 2.4: is. arranged laxially of the Vdriving raeefl and atoneendihasanannular taperediiange 23-whiclf1-loosel's nests within theshallowraxiall counterbore in thel groove'd surface: of driving racellS.Pin"24-is adapted forrsl-idable positioningwithin the bore ofthe-centeringspindle 3.7i,

whose-opposite end-is substantially hemispherical as at 36 for; szaxial;.engagement .-within the? tapered NGGSS "i315 is interposed incompression, between flange 23 and the annular shoulder 38 on saidspindle. Accordingly, upon completion of the assembly of the tool holderand tightening of the housing 21 there is provided an initial axialpreloading of the movable parts of the tool holder whereby the drivenmember is initially positioned in longitudinal alignment with thelongitudinal axis of the driv- .ing shank 11 and the driving race 18.The centralizing assembly is effective for this purpose because llange23 is loosely retained in driving race 18 against radial displacement.Pin 24 guidably and slidably engages spindle 37 which is biased axiallyoutward under the action of compressed spring 39.

While the centralizing device is convenient in conjunction with thepresent construction, being loosely positioned through the centralaperture 30 of the oat 25, nevertheless, this centralizing device is notabsolutely essential and could be omitted.

Flange 32 of driven member 31 is arranged at right angles to thelongitudinal axis of the driven member and in the end face of said angethere are formed a series of parallel spaced grooves 33 of arcuate fromin crosssection. These grooves in the initial assembly of the deviceextend in the direction at right angles to the series of ball receivinggrooves 21 formed in driving race 18, and are adapted to cooperatelyreceive the bearings 27 in conjunction with the float mechanism 25 nowdescribed.

Interposed between driving race 18 and ange 32 of driven member 31 thereis provided an intermediate driving race or oat 25 which is of lessexternal diameter than the internal diameter of retainer housing 21. Inone end face of float 25 there are formed a series of parallel spacedelongated grooves of arcuate shape in crosssection which are arranged inopposed relation to the corresponding grooves 21 formed in race 18. Thegrooves 26 and 21 cooperatively receive therebetween a series ofbearings, which in this embodiment are ball bearings 27 which areloosely mounted within the ball retainers 28, of which there are four inthe present embodiment.

The only function of the retainer is to retain the balls in suitablerelative positions, each retainer having a series of circular transverseapertures which loosely receive the said ball bearings 27 and maintainthem in a circular arrangement, such as illustrated in Fig. 6. Theseretainers lie loosely in their alloted space and cause no friction, andthemselves have no contact with the driving race 18 or intermediatedriving race 25.

There are also formed within the opposite face of float 25 anotherseries of parallel spaced grooves 29 which are of similar arcuatecross-section and which cooperate with and are in opposed relation tothe series of spaced grooves 33 in the end face of ange 32 for receivingthe second series of bearings 27 within their retainers 28.

Accordingly, the series of grooves 29 extend in a direction at rightangles to the series of grooves 26 on the opposite side of float 25.

In other words, the driving relation between driving race 18 and theflange 32 of the driven member is strictly through the balls 27 arrangedupon opposite sides of float 25 and movably mounted respectively Withinthe above described grooves. Accordingly, as viewed in Fig. 1, the oat25 is restricted to movements with respect to race 18 in the directionof the slots 21 and 26, i. e., normally of the plane of the illustrationof Fig. 1.

This means'that the driven member 31 which is joined by the oat 25 torace 18 through the said balls is thereby controlled for transverseadjustments in this same direc,- tion, i. e., normally in the plane ofthe illustration.

Additionally, in view of the right angularly related grooves 29 and 33and the second set of bearings 27 between flange 32 and oat 25, the saiddriven member is also adapted for transverse adjustments in the plane ofthe illustration of Fig. l with respect to the said lloat.

Accordingly, in view of the above described assembly, the driven membermay move simultaneously in either the plane of the illustration'or atright angles thereto and, consequently, in any direction which is aresultant of these two movements. In other words, the driven member maytloat in any direction in a plane normal to the longitudinal aXis of thecoupling.

In view of the axial preload which is introduced between the movingparts of the coupling and in view of the grooves provided, as well asthe bearings interposed between the moving parts and stationary parts,all such transverse movements of the driven member 31 with respect tothe driving race 18 will be such that the longitudinal axis of thedriven member, as well as the tool T will be in planes parallel to thelongitudinal axis of the shank 18. In other words, the presentconstruction will maintain a parallelism between the respective axes ofthe shank 11 and the driven member 31.

Thrust bearing means are also employed in conjunction with the side ofange 32 opposite from its grooved end face, which bearing meanscooperate with ange 22 of retainer housing 21 for completing theassembly of the coupling and for imparting to the movable parts thereofan initial axial preload.

For this purpose, and in the preferred embodiment of the invention,there are provided a series of thrust bearing elements 41, 43 and 48,which are of a construction quite similar to the ball and groovearrangement above described in conjunction with members 18, 25 and 32.

Mounted upon the shoulder 40 of driven member 31 there is providedthrust race 41 of less diameter than the internal diameter of retainer21', and in the outer end face thereof there are formed a series ofparallel spaced grooves 42 for receiving the bearings 45, which in thepreferred embodiment are ball bearings. Intermediate thrust race 43 isloosely positioned around driven member 31 and in one face thereof hasformed therein a series of parallel spaced grooves 44 of arcuatecross-section which are arranged in opposed relation to grooves 42 andcooperate therewith for retaining the series of circularly arranged ballbearings 45, and their bearing retainer 46 which is loosely interposedbetween races 41 and 43.

The opposite end face of floating thrust race 43 has a second series ofparallel spaced grooves 47 adapted to cooperatively receive the set ofbearings 45 within their retainer 46.

There is also snugly provisioned within the end portion of retainer 21 athird thrust race 48 as indicated at 51; and in the inner end face ofthis member there are provided a series of parallel spaced grooves 49 ofarcuate cross-section which are arranged in opposed relation to thetransverse grooves 47 formed in intermediate thrust race 43, and whichcooperate therewith for supporting therebetween the ball bearings 45.

Here also the grooves 47 and 49 extend in a direction at right angles tothe direction of the grooves 42 and 44 so that the functioning of theset of thrust races is exactly the same as the functioning of themembers 18, 25 and 32, to thereby establish a free floating relationshipbetween the respective parts between thrust races and the driven member31.

Upon proper tightening of the retainer 21 with respect to the threads 13and functioning through the above described thrust races there is thusinitially attained an axial preloading of the moving parts of thepresent coupling.

This axial preload through each of the sets of bearings and incooperation with the respective opposed grooves initially retains therespective parts of the coupling in axial parallelism. Should there beany msalignment between parts, guarantees` 4that vthev respective axesof .thefdriven ,'member and. the vshanlowill, at all times. beparallel,Ato `thereby attain thefobjects above setlortli.

5 the longitudinal axes of `'the driven memben aleand the driving shank1l1then`in that case the said arrangement|` of Annlardisc SZis"mmovablysecured upon the `exterior the interior thereof.

The -outer end of Afdriven member j 31 is exteriorly threaded as at 54and is adapted to -threadedly receive the `cap 55 which'at'one end la'sa Acentrallyapertured annular Fb'ot'tom flange 56-whichretaininglyengages the adaptor 58 @for the tool T which may be atap or'areamer or other tool. p

The inner surfaceof 'the endportio'n 54 of the driven member `311 Vis,tapered as, at"57"for cooperatively Avretaining f@ engagement with acorrespondingly'shaped endpoition of adaptor 58 whereby the tool iseffectively gripped within the bore 59 at the outer end of driven member31.

While in the preferred embodiment ball bearings have been described,Figs. 7, 8 and 9 show the use of other types of bearings which willfunction just as well in the present construction; it being the primaryobject that the bearings between the respective parts provide linecontacts between the relatively movable elements of the coupling.

For example, in Fig. 7 the two relatively movable elements 60 and 61have formed therein opposed elongated parallel grooves 62 and 63 forcooperatively receiving the series of rollers 64 which will functionjust as well as the ball bearings 27.

In Fig. 8, the pair of opposed elements 65 and 66 have formed thereinopposed parallel transverse grooves 67 and 68 which cooperativelyreceive therebetween the rollers 69. Additionally, Yin the opposingsurfaces of elements 65 and 66 there are formed parallel elongatedopposed rows of grooves 70 and 71 which cooperatively receive ballbearings 72. Accordingly, there may be a combination of ball bearingsand roller bearings to thereby provide lines of contact between therelatively movable parts of the holder.

Figure 9 illustrates still another slight variation wherein, forillustration, a pair of relatively movable parts 73 and 74 have formedin their opposed end faces a series of parallel spaced grooves 75 and 76which cooperatively receive therebetween a series of special formedbearings 77, which also provide and assure between their respectiveelements parallel lines of contact therebetween for thereby minimizingfriction.

As above described, by interposing bearings 27 between driving race 18and intermediate race Z5; and by interposing an additional set ofbearings 27 between intermediate Irace and the driven member 31, adriving relation is established between the said parts whereby rotativepower transmitted through race 18 will effect rotary movement of thedriven member 31 with a minimum of friction.

Furthermore, since all the moving parts and the interposed balls areheld together under a strain or preload by the retainer 21', drivingmember 11 and driven member 31 are maintained axially parallel to oneanother and resist any bending moment about their axes.

In the above floating coupling, no fixed or moving part is in slidablecontact with any other part. Instead, there is a pure rolling actionthrough the medium of the bearings which roll freely on imaginary axes.Consequently, the relative movement of the parts is as nearlyfrictionless as possible, and friction in the present construction doesnot increase appreciably with the load.

Another important feature of the present invention is that the ballscontact the respective mating surfaces ofthe adjacent parts along linesof contact instead of at points and, consequently, the present devicewill withstand much greater loads over a long period of time, thusextending the life ofthe device.

..Brinellng of. surfaces; ,isi .overcome and v,prennent.eil/:by

.t `supportably .positioning the i balls within` grooved faces,

with the vballs Vlitting the groovesvat llines. of contact.

K. Having ,describedmyh inventlonpreference lshould `now be had .to itheclaims which follow -for determining-the .scope thereof.y

I claim: p Q

l. A- ylloating'v ltool holder-comprising a driving-shank. .rotatable on`itslongitudinal axis and having atrend, face' at right` angles to saidaxis, a disc shaped driving `race axially secured uponrysaidvend faceand having formed Y in'its outer face a j series of parallel spacedgrooves of arcuate crosssection, :anielongatedmdriven member 4Vcop axialwith said `rsh-ank. havinganfaxialbore lat one end to Vreceive 'a tool-andfatitsjother endan end face 'at 'fright angles to said axisspac'edfrom, said driving race, and'having formed therein aseries 'ofparallel 'spaced grooves 'of varcuate Across section extendingeat rightlangles to said Vfirst grooves, 'aninterm'ediate disc shaped drivingrace Vspaced from and between :.saiditdriving race and driven-member,one face of ysaid intermediate race having a 'series of parallel spacedgrooves of arcuate cross section larranged in opposed relation to thegrooves of lsaid driving race, its other face having a series ofparallel spaced vgrooves of arcuate cross -section extending at rightangles to the grooves in said one face Aand arranged in opposedrel-ation to the grooves on the end face of the driven member, retainerdiscs intermediate opposite sides of the intermediate race and the driverace and driven member, Irespectively, bearings in said retainersmovably mounted in the respective opposing grooves deining lines ofcontact between opposing members, -a retainer housing loosely enclosingsaid races and driven member at one end threaded to said shank, saiddriven member having a at radial shoulder, s-aid retainer housing havinga flat radial inner face, a thrust race axially mounted on said drivenmember having one at end face at righ-t angles to said axis engagingsaid shoulder with a series of parallel spaced grooves of arcuate crosssection formed in its opposite end face, a second co-axial thrust racemounted on said retainer housing and having one at end face at rightangles to said axis engaging the inner face of said retainer with aseries of parallel spaced grooves of arcuate cross section formed in itsopposite end face extending in a direction at right angles to thegrooves in said thrust race, an intermediate thrust race spaced betweensaid thrust races with its opposite sides having formed therein a seriesof parallel spaced grooves of arcuate cross section with the grooves onone side in opposed relation to the grooves in the rst thrust race andwith the grooves on its other side in opposed relation to the grooves insaid second thrust race, and bearings with retainers movably mounted inthe respective opposing grooves of said thrust races defining lines ofcontact there between, vsaid retainer housing applying an axial preloadto said thrust races and other moving parts.

2. A oating tool holder or coupling comprising a driving memberrotatable on its axis and having a series of parallel spaced grooves ofarcuate cross section in its end face, a driven member co-axial with thesaid driving member, an annular ange on one end of the driven member,the outer and inner faces of the flange each having therein a series ofparallel spaced grooves of arcuate cross section, the other end of thedriven member being extended and having an axial bore to receive a tool,an intermediate annular driving member having a series of parallelspaced grooves on one face and a similar series of grooves on the otherface but arranged at right angles to the grooves on said first face,this intermediate driving member being between and spaced from thegrooved face of the driving member and the grooved outer face of thedriven member flange, an annular end thrust race having parallel groovesof arcuate cross section on one side and a plane surface on the otherside, an intermediate annular thrust race, having parallel grooves ofarcuate cross section on one face and similar grooves on the other facebut arranged at right angles tothe grooves on its rst face, thisintermediate race being between and spaced from the inner face of thedriven member flange and the inner face of said end thrust race, foursets of balls, one set each being between and engaging appropriateadjacent grooves in the driving and intermediate driving members, theintermediate and driven members, the driven and intermediate thrustmembers, the intermediate thrust and end thrust members, respectively,and a retainer housing threaded to said driving member loosely enclosingIand applying an axial preload to the moving parts, said floating toolholder or coupling comprising `specifically four distinct sets of ballsarranged in parallel planes at right angles to the axes of the driving4and driven members, each set operating in parallel spaced grooves ofarcuate cross section formed yon the transverse faces of the essentialparts in Isuch manner as to allow movement in any direction at right`angles to the axes.

slidably extending into said bore and aeaepas 3. The tool holder ofclaim l, and a centralizing device intermediate said driving race anddriven member consisting of an axial thimble having an axial bore at oneend, its opposite end being hemispherical and centrally engagingin'retaining relation saidvdriven member, said thirnble having anannular shoulder, an elongated pin at one end having an annular angecentrally nested loosely within the driving race, and Ia coiled springunder compression interposed between said flange and shoulder.

References Cited in the file of this patent UNITED STATES PATENTS1,907,447 Schiltz May 9, 1933 2,371,330 Irstad Mar. 13, 1945 FOREIGNPATENTS 381,319 Great Britain Oct. 6, 1932 613,788 vGreat Britain Dec.2, 1948

